Floating mandrel for drawing welded tubes with longitudinal seam

ABSTRACT

A floating mandrel for drawing welded tubes with longitudinal seam, comprising two cylindrical sections of different diameters interconnected by a tapered section. One cylindrical section having a larger diameter incorporates a guiding slot while the other section having a smaller diameter incorporates a throughhole extended to the surface of the mandrel which contacts the tube, thus forming a cutting edge. This edge is encompassed by a groove made in the contacting surface and extended to the cylindrical section having a larger diameter.

United States Patent [1 1 Alekhin et al.

[4 1 Sept. 9, 1975 FLOATING MANDREL FOR DRAWING WELDED TUBES WITH LONGITUDINAL SEAM Inventors: Leonid Pavlovich Alekhin,

Filed:

Matveevskaya ulitsa, 6, kv. 56, Moscow; Albert Viktorovich Anisimov, Novomytischinsky prospekt, 23/7, kv. I02, Mytischi Moskovskoi oblasti; Vadim Ivanovich Vikulov, Dubninskaya ulitsa, 63, korpus I, kv. 56, Moscow; Veniamin Alexeevich lshunkin, ulitsa Tolbukhina, l2, kv. 86, Moscow; Vyacheslav Fedorovich Kleimenov, Matveevskaya ulitsa, l0, korpus 3, kv. 9, Moscow; Mikhail Zelikovich Lokshin, Slavyansky bulvar, 27, kv. 37, Moscow; Vladimir Alexandrovich Moshkin, Kutuzovsky prospekt, 33, kv. I02, Moscow; Vadim Yakovlevich Shapiro, ulitsa Govorova, l6, korpus 2, kv. 10, Moscow, all of USSR.

Sept. 17, 1973 Appl. No: 398,098

US. Cl 72/283; 72/44 Int. Cl. BZlc 1/24 Field of Search 72/283, 41, 43, 44, 45;

[56] References Cited UNITED STATES PATENTS 2,l83,361 12/1939 Cotter 72/44 2,355,734 8/1944 Katz 72/283 3,055,]02 9/[962 Shaw ct al. 72/4I 3,5I3,682 5/1970 Rowcll 72/283 FOREIGN PATENTS OR APPLICATIONS 655,930 8/1951 United Kingdom 72/45 OTHER PUBLICATIONS Abstract: U.S.S.R. lnventors Certificate, No. 300,232, Moshkin, V. A. et al. 5287l.

Primary ExaminerC. W. Lanham Assistant ExaminerM. J. Keenan Attorney, Agent, or FirmWaters, Schwartz & Nissen [57] ABSTRACT A floating mandrel for drawing welded tubes with longitudinal seam, comprising two cylindrical sections of different diameters interconnected by a tapered section. One cylindrical section having a larger diameter incorporates a guiding slot while the other section having a smaller diameter incorporates a through-hole extended to the surface of the mandrel which contacts the tube, thus forming a cutting edge. This edge is encompassed by a groove made in the contacting surface and extended to the cylindrical section having a larger diameter.

2 Claims, 3 Drawing Figures PATENTED 1975 SHEET 1 UF 2 2 j M: V

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F IE. 2

FLOATING MANDREL FOR DRAWING WELDED TUBES WITH LONGITUDINAL SEAN! The present invention relates to the tube production and more exactly to floating mandrels for drawing welded tubes with longitudinal seam.

The present invention may be most efficiently uti lized in drawing thin-walled tubes made from materials tending to excessive sticking, such as aluminium and its alloys.

Floating mandrels are known at the present time for drawing welded tubes with longitudinal seam. compris ing two cylindrical sections of different diameters of in terconnccted by a tapered section with one section of a larger diameter incorporating a longitudinal guiding slot to orient the mandrel with respect to the internal flash and with the other section of a smaller diameter incorporating a through-hole to pass the removed internal flash into the drawn portion of the tube. the latter hole directed from the end face of this section towards the guiding slot and extended to the surface contacting the tube thus forming a cutting edge of the mandrel lcll. see USSR Author's Certificate No. 300,232 cl B 21 c, 3/16).

ln drawing tubes using known mandrels, the section of the inner surface of the tube corresponding to a spot from which flash has been removed enters the wall re duction zonc with minimum amount of lubricant be cause the major portion of this lubricant is carried away together with flash removed. Therefore in drawing tubes made from materials tending to excessive sticking. sci/ing occurs between the metal and the contacting surface of the mandrel, which results in notches and scores on the inner surface of the tube in the flash removal lone thus reducing the quality of this inner sur face.

The object of the present invention is to obviate the above disadvantage.

An important object of the invention is to provide a mandrel for drawing welded tubes capable of obtaining the inner surface of the tube of the required quality with simultaneous removal of internal flash by way of maintaining the needed amount oflubricant in the wall reduction zone over the entire perimeter of the tube.

These and other UhJCLlS are achieved due to the proiision of a floating mandrel for drawing welded tubes comprising two cylindrical sections of different diainc ters interconnected by a tapered section with one of them of a larger diameter incorporating a longitudinal guiding slots to arrnage the mandrel with respect to the internal flash and with the other of a smaller diameter incorporating a through-hole to pass the internal flash remoicd in the course of drawing, into the drawn portion oithe tube, the latter hole being directed from the end face ofthis section towards the guiding slot and ex tended to the surface of the mandrel which contacts the tube. thus forming a cutting edge. according to the invention the surface ofthc mandrel contacting the tube incorporates a grome encompassing the cutting edge and cttcnded to the cylindrical section of the larger diamctcr.

lhis design of the mandrel is capable ot'obtaining the inner surface of the tube of the required quality because the groove made in the surface of the mandrel contacting the tube brings lubricant in the course of drawing to that section of the tube from which flash has just been removed, thus preventing metal sticking on the surface of the mandrel contacting the tube.

Conveniently the groove takes the shape of a secondorder curve whose vertex is away from the cutting edge through a distance equal to 0.2 to 2.0 of the thickness of the tube wall while its legs are inclined in relation to the guiding slot at an angle of 15 to 45.

Significantly important with this groove is its shape and positioning in relation to the cutting edge. Their best relative arrangement is when this groove delivers the sufficient amount of lubricant without substantial decrease in the strength of the mandrel All these requirements are fully met with the above configuration of the groove. Moreover, arrangement of the groove legs at an angle to the longitudinal slot helps to obtain the tube inner surface of the required quality.

However, it the above limits are not observed by locating the vertex of the curve away from the cutting edge through a distance exceeding 2.0 times the value of the tube wall thickness or less than 0.2 oi said value the reduction zone will lack lubricant or the mandrel be of less stability. Location of the curve legs at a larger than 45 angle will lead to an insufficient amount of lu bricant brought to the tube section which has been freed from flash. This will be caused by the extended length of the groove and by carrying away a certain amount oflubricant by the passing adjacent sections of the tube. On the other hand. location of the curve legs at a less than 15 angle may cause clogging of the curve with the tube metal at the point where the reduction zone begins.

In order to make the invention more readily understood a specific embodiment thereof will now be de scribed with reference to the accompanying drawings, in which:

FIG. 1 is a fragmentary cutaway view of the mandrel according to the invention;

FIG. 2 is a plan view of the mandrel shown in FIG.

P36. 3 shows the same mandrel in the course of tube drawing.

The mandrel comprises two cylindrical sections 1 and 2 (HO. 1) of different diameters with the section 1 having a larger diameter and the section 2 a smaller diameter. Both these sections are interconnected by a tapered section 3. The section 1 incorporates a longitudinal guiding slot 4 to arrange the mandrel with respect to the internal flash, while the sections 2. and 3 incorporate a through-hole 5 to pass a removed internal flash (i into a drawn portion of a tube 7 (FIG. 3). This hole is directed from an end face 8 (HG. 2) of the section 2 towards the guiding slot 4 and extended to a surface 9 of the mandrel contacting the tube 8, thus forming a cutting edge it).

The surface 9 incorporates a groove ll encompassing the cutting edge 10 and extended to the cylindrical section 1. This groove brings the suflicient amount of lubricant to the tube wall reduction zone. thus prevent ing metal sticking on the surface 9 of the mandrel contacting ihc tube To avoid any substantial reduction in the strength of the mandrel the groove is given a sccond-ordcr curve configuration such as that oi a parabola shown in FIG. 2.

The vertex *A ol'the parabola is away from the cut ting edge Ill through a distance i" which is equal to 0.2 to 2.0 ol the thickness of the wall of the tube 7. Legs B of this parabola are inclined in relation to the guiding slot 4 at an angle a within the range of to 45.

EXAMPLE Drawing of welded tubes of diameter zl= 55 mm and wall thickness S L65 mm to obtain the tube size of diameter d 50 mm and wall thickness S 1.5 mm made from an alloy based on aluminium with the addition of Cu 3.8-4.9 percent. Mg 0.4-1.8 percent, Mn 0.3-0.9 percent. admixtures making up the balance, is effected by means of a mandrel incorporating a parabolic-shaped groove.

The vertex of the parabola is away from the cutting edge of the mandrel through a distance a l.5 mm while its legs are inclined in relation to the longitudinal guiding slot at an angle a= 25. This mandrel is capable of obtaining tubes with the inner surface of high quality due to the delivery of the sufficient amount of lubricant via the circular lubricating groove to the reduction zone.

What we claim is:

l. A floating mandrel for drawing welded tubes with longitudinal seam, comprising: two cylindrical sections of different diameters; a tapered section interconnecting the cylindrical sections. said sections having a surface contacting an inner surface of the tube. one of said cylindrical sections having a larger diameter, the second cylindrical section having a smaller diameter and an end face; a longitudinal guiding slot to arrange the mandrel with respect to an internal flash in said second cylindrical section having a larger diameter; a through hole to pass the internal flash removed in the course of drawing into the drawn portion of the tube in said cylindrical section having the larger diameter and directed from the end face of this section towards the guiding slot and extending to said surface of the mandrel with contacts the tube, thus forming a cutting edge; a groove in said contacting surface and encompassing said cutting edge and extending to said cylindrical section having the larger diameter to pass lubricant applied in advance to the inner surface of the tube to the reduction zone behind said cutting edge in the course of drawing.

2. A mandrel as set forth in claim 1, wherein said groove has the configuration of a second-order curve whose vertex is away from the cutting edge through a distance of 0.2 to 2.0 of the thickness of the tube wall while the legs thereof are inclined in relation to the longitudinal slot at an angle of 15 to 45.

i h l 

1. A floating mandrel for drawing welded tubes with longitudinal seam, comprising: two cylindrical sections of different diameters; a tapered section interconnecting the cylindrical sections, said sections having a surface contacting an inner surface of the tube, one of said cylindrical sections having a larger diameter, the second cylindrical section having a smaller diameter and an end face; a longitudinal guiding slot to arrange the mandrel with respect to an internal flash in said second cylindrical section having a larger diameter; a through-hole to pass the internal flash removed in the course of drawing into the drawn portion of the tube in said cylindrical section having the larger diameter and directed from the end face of this section towards the guiding slot and extending to said surface of the mandrel with contacts the tube, thus forming a cutting edge; a groove in said contacting surface and encompassing said cutting edge and extending to said cylindrical section having the larger diameter to pass lubricant applied in advance to the inner surface of the tube to the reduction zone behind said cutting edge in the course of drawing.
 2. A mandrel as set forth in claim 1, wherein said groove has the configuration of a second-order curve whose vertex is away from the cutting edge through a distance of 0.2 to 2.0 of the thickness of the tube wall while the legs thereof are inclined in relation to the longitudinal slot at an angle of 15* to 45*. 